1. Field of the Invention
The invention generally relates to simple, efficient means for coupling the light output of a laser into utilization apparatus. In particular, coupling is made directly through a contiguous broad wall of the wave guide, and no additional optical components such as lenses, fibers, or gratings are needed.
2. Description of the Prior Art
The direct light beam produced by known prior art semiconductor diode lasers is inherently relatively divergent with respect to the light beam from a conventional gas laser, for example, so that lenses are normally required to collect, collimate, and focus the diode laser light beam. Flat optical fiber bundles have also been used to collect light from semiconductor lasers; once the light is collected by such fiber bundles, it may be coupled to a thin film wave guide by butting the output end of the bundle against the edge of the wave guide. The use of miniature cylindrical or spherical lenses has been suggested as a more direct means of coupling semiconductor lasers to optical wave guides.
However, each of the known prior art coupling systems has one or more defects. Above all, any use of a macroscopic element with a semiconductor laser, which is inherently a miniature device, defeats the objective of fully retaining its miniature character. Any use of prisms, tapers, gratings, or the like at once reduces the possibility of a miniature design fully suited to manufacture by the application of known microcircuit techniques. While such couplers are generally effective in collecting the laser light, the coupling function is performed in an inefficient manner.